Gaseous-conductor lamp.



D. McF. MOORE.

GASEOUS CONDUCTOR LAMP.

APPLICATION FILED MAY], l9l4.

Patented June 20, 1916.

\nventor: DamelcFarlan moors H is At orneg UNITED STATES PATENT OFFICE.

DANIEL MOFARLAN MOORE, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO GENERALELECTRIC COMPANY, A COBIPORATION OF NEW YORK.

GAsEoUs-coNnUoron LAMP.

Specification of Letters Patent.

Patented June 20, 1916.

Application filed May 7, 1914. Serial No. 836,871.

I '0 all whom it may concern Be it known that I, DANIEL MCFARLAN Moons,a citizen of the United States, residing at East Orange, county ofEssex, State of New Jersey, have invented certain new and usefulImprovements in Gaseous-Conductor Lamps, of which the following is aspecification.

My invention relates to vacuum tube devices in which an electricaldischarge takes place between electrodes in a vessel containing more orless rarefied vapors or gases, and more particularly to devices of thischaracter in which the electrical discharge spects my invention relatesto devices of this character regardless of the particular gas or vaporused, although in other respects it especially relates to gases of highconductivity, such as neon, or similar gases which have a comparativelyhigh conductivity and emit a light suitable for the purpose desired..

The principal object of my 1 nvent10n 1s to produce a gaseous conductiondev ce which is particularly adapted to utilize neon as a gaseousconductor.

A further object is to provide improved electrodes by means of which theoperation of gaseous conductive devices in general may be improved andtheir efliciency 1ncreased.

A further object is to provide gaseous conduction lighting devices whichWlll operate either on alternating or direct current, and which are socompact as to be comparable in dimensions with theincandescent lampscommonly used.

Another object of my invention 1s to so combine the electrodes and thegas or vapor that the potential between the electrodes and the gaseousconductor is reduced to a minimum.

A still further object is to improve gaseous conduction devicesgenerally and in various details of construction as hereinafter morefully described.

To this'end my invention comprlses various novel features and details ofconstruction which are more f lly hereinafter described and pointed outwith'particularity in the appendedclaims.

Merely for purposes of illustration I have shown in the accompanyingdrawings some of the many various forms in which 'my invention mav beembodied, and in which- Figure 1 is a longitudinal section through alamp suitable for operation on direct current and provided with improvedelectrodes constructed in accordance with my invention; Fig. 2 is alongitudinal section of a similar lamp having a short gaseous Y columnand rovided with a difierent form of cathode; ig. 3 is a diagram ofconnections, showing how a plurality of various forms of lamp embodyingmy invention may be connected inparallel and all may be started by aninductive discharge if necessary; Fig. 4 is a View partly in section ofa lamp provided with other forms of electrodes; Fig. 5 is a view partlyin section of a straight tube gaseous lamp provided with an automaticfeed valve and having an improved electrode constructed in accordancewith my invention; Fig. 6 shows a lampcontaining neon and constructed tooperate upon alternating current.

The particular form of device which I have illustrated in Fig.1 as oneembodiment of my invention is a gaseous conduction device suitable forthe production of light and made of the general form and dimensions oflamp shown in Fig. 1 comprises a bulb 1 containing a suitable atmospherewhich may be any gas suitable for the purpose,

such as nitrogen or carbon dioxid, but which is preferably one of therare gases of good conductivity, such as neon or helium, or a f similargas. In order that the light giving column may be of considerablelength, I

provide suitable means for compelling the discharge to take a more orless tortuous course inside the bulb 1. In the particular device shownin Fig. 1 this result isattained by means of a directing device orbarrier 2,

1 preferably made in the form of a tube of glass or similar material,and suitably mounted in the bulb so as to extend longitudinally of thebulb. The barrier is pref- -such a manner that there is nocommunicaerably sealed to the neck of the bulb in tion between the spaceinside of the tube 2 and the interior of the bulb except through theopen end of the tube.

In accordance with my invention one of the electrodes is mountedoutsidethe'tube 2 "near the-neck of the bulb and the other is mountedinside the tube so that the electrodes are substantially concentric butare separated by the walls of the tube 2. In devices of this form Iusually prefer to make the electrodes of a suitable metal, such as purealuminum, which does not contain any trace of iron or other deleteriousmaterial. Any traces of foreign materials combined with the aluminumtend to cause dark deposits in the tube and to increase the difiicultiesof exhausting it. I have found that these difliculties are eliminated ifthe aluminum is really pure. One of the electrodes, preferably the anode3, is mounted outside of the tube 2 near the neck of the bulb. The otherelectrode or cathode 4 is mounted inside the tube 2 and comprises achamber of some suitable metal such as pure aluminum. This chambercontains some material 5 which will decrease the resistance to thepassage of current between the gaseous conductor and the electrode, andwill not appreciably attackthe material of the chamber.

The electrode material which I prefer to use in the aluminum chamber ismetallic sodium, or an alloy or mixture containing metallic sodium. Thealuminum chamber may be shaped in various ways as long as it acts as acontainer and holds the electrode material in such a manner that thematerial is in contact with the gaseous conductor of the lamp. Theparticular cathode shown'is provided With a rentrant tube 6 whichprevents ispilling of the metallic sodium 5 when the lamp is moved whilethe sodium is very hot, and also provides an orifice for exposing thesodium to the gas in the lamp. Usually the sodium remains in thealuminum cup because of its adhesion to the alu- 5.5 ing the electrodesand preferably formed in the tube 2.

When the lamp is in operation the discharge takes place between theanode 3 and the cathode. ,The discharge is compelled to traverse thelength of the tube 2 and then return, hence the light giving column islong. Owing to the novel construction of the cathode the losses at theelectrodes are imized and consequently the efficiency of sired, ofaluminum' and metallic sodium,

risaiea Fig. 2 the bulb 1 contains some suitable gas,

such as neon, and is provided with an anode 10 consisting of aluminum,iron, tungsten or similar metal. It may be, if desired, cup shaped andcontain some suitable material, like metallic sodium.- It is preferablyso proportioned that a large surface is exposed to the neon. The cathodeis mounted near the other end of the bulb in any suitable way, as forexample, on the end of a pedestal 11.

like the cathode 4 shown in Fig. 1. In the particular form shown in Fig.'2 the nega tive electrode is constructed of some refractory material12, such as boron nitrid,

pressed refractory oxids of calcium, zirconlum, thorium, or simllarmater-la], and

has one or more constricted passages or.

lamp. The material 12 should be a poor conductor of heat and preferablyvery re- It may be constructed, if de fractory so that the dischargethrough the constricted passage 13 will heat the small body of gaslnclosed in the passage to a high temperature and thus in turn heat thewalls of the passage. This hi h localized heating facilitates thetransfer 0 current between the electrode and the gaseous conductor andin conjunction with neon makes the lamp a very efficient light producingdevice.

In exhausting gaseous conduction lamps, and particularly thoseconstructed to embody my invention, all traces of foreign gases shouldbe removed so that when completed the lamp will contain only the gaseousconductor which is to be used. This 15 particularly important where thelamps contain neon as the gaseous conductor. It is therefore desirablethat the lamps be thoroughly heated and exhausted and that by repeatedadmission and exhausting of a suitable gas all impurities and occludedgases be washed out of the lamp so that when the neon is finallyadmitted no deleterious foreign gases will mix with it and impair itsefficiency. In some cases it may be advisable to wash out the lamp onceor twice with neon before finally sealing the lamp off from the pumps,even though the lamp has previously been washed out a number of timeswith some suitable gas such as nitrogen for the purpose of getting ridof the water vapor and occluded gases driven out of the electrodes and.the walls of the tube by heat. If the lamp is to be operated withnitrogen, for example, instead of neon, the washing will be repeated atnumber of times with nitrogen untll only pure nitrogen remains in thelamp atthe proper pressure, whereupon the lamp is sealed off from thepump.

The losses in a gaseous conduction device are the result of thenecessity of the electric current changing the medium through which ispasses. In general, if the current passes through a solid to a liquid,and thence to the gaseous conductor, the loss is less than if thecurrent passes immediately from the solid conductor into the gaseousconductor. This is particularly the case if the solid conductor is cold,and the gaseous conductor is hot, as it must be while the lamp isrunning. In accordance with my invention a vapor may be generated nearthe solid conductor to cause the conditions adjacent the solid conductorto be such that flow of current into the gaseous conductor isfacilitated. Where the vapor is generated from a refractory material Iprefer a construction, such as that shown in Fig. 4, comprising a funnel34 with a constricted vent or orifice 35 opening into a receptacle 33.Both the funnel and the receptacle are lnade of very refractoryinsulating material, such as fused silica. In many cases I construct theevacuated envelop of fused silica, particularly where neon is used asthe gaseous conductor, and thereby secure longer life, greater intensityof current flow and higher efiiciency, and in general improve the neonlamp. In the receptacle 33 I place the vaporizable electrode material36, which may be metallic sodium, or a mixture containing sodium, as forexample a mixture of approximately 65% sodium, 30% mercury, and 5%potassium, or may be a more refractory electrode material, such ascarbon in such a condition that carbon vapor will be generated when thelamp is in operation at a suitable current density. The,

current flow is so concentrated on the electrode material in thereceptacle 33 that an atmosphere containing suitable vapor is generatedin the receptacle 33 and facilitates the transfer of current, therebyincreasing the eiiiciency of the. lamp. The

.I shape of the receptacle 33 and the constricted' orifice prevents thevapor in the receptacle passing out into the lamp to any great extent.

Gaseous conduction devices constructed in accordance with my invention,and especially those containing neon, will operate in parallel and willstart on voltages substantially the same as or only slightly above thenormal operating voltage. In some cases it may be desirable to providemeans for momentarily impressing a higher voltage upon the circuit toinsure the starting of all the lamps. One way of showing this is showndiagrammatically in Fig. 3, in which the circuit containing a reactance24 is provided with a circuit interrupting device 25 connected inparallel with the lamps, which may be of the various types shown in thedrawings as examples of embodiments of my invention. This circuitinterrupting device 25 may be a quick break switch or any other similardevice by means of which potential upon the circuit may be mo--mentarily raised for the purpose of starting the lamps connected to thecircuit in parallel.

In many cases it is desirable to operate lamps upon an alternatingcurrent system, and by my invention I provide gaseous conduction lampswhich will so operate. One form of such 'a lamp is shown in Fig. 4, inwhich the bulb 28 containing neon or other gas of good conductivity isprovided with a central tube 29 similar to the tube 2 of former of theusual type.

Where'it is desired that the tube have a 'very long life, provision mustbe made for automatically adding more neon as the original charge isconsumed. A suitable arrangement for doing this is shown in Fig. 5, inwhich the tube 51 is provided with an aluminum electrode 52, and anelectrode 58 of sodium or of cups 49 formed of aluminum and containing'metallic sodium 50. By

means of an automatic electromagnetic feed valve 53 constructed inaccordance with my Patent 1,032,927, issued July 16, 1912, small amountsof neon may be automatically admitted to the tube from a reservoir orsupply tank 54. In some cases it maybe advantageous to so arrange thedevice that the valve is supplied with neon only at the will of theoperator, so that the operator can take precautions to insure the purityof the neon fed to the tube, although the amount fed is controlledautomatically by the valve. This result may be accomplished in manydifferent ways, as for example by means of the valve 55 controlling theoutlet of the tank 54 and the valve'56 which controls the flow of neonto the automatic feed valve 53. A purifier 57 ofsome suitable design isattached to the feeding system and may, for example, consist of a glasschamber containing charcoal or similar absorbent material, the wholebeing so constructed that the chamber may at will be immersed in liquidair or similar refrigerating means, to cause the charcoal to absorb thelast traces of foreign gases from the neon. When the operator sees thatthe lamp should be supplied with more neon he can admit a small amountof neon into the purifying chamber 57 and then after purifying it bycooling the chamber he can admit the purified neon from the purifier 57to the automatic feed valve 53 which will thereupon feed into the tubethe right amount of neon to bring the pressure in the tube back to theproper point.

In many cases it is desirable that the gaseous conduction lamp shalloperate with an arcing discharge lamp upon an alternating currentcircuit. I have shown such a lamp in Fig. 6, in which two anodes 60 and61 are connected respectively to the opposite terminals of thetransformer winding 62, of which the middle point is connected to thecathode ($3. The cathode is preferably an aluminum cup containingmetallic sodium. The reactance of the circuits through the transformerwindings is such that an arcing discharge is maintained through thegaseous conductor, which is thereby rendered continuously luminous.

My invention may be embodied inmany I other forms than those shown anddescribed, and I therefore do not limit my invention to the precisearrangement disclosed, except in so far as it is limited by the scope ofthe appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. In a gaseous conduction lamp, the combination with a sealedreceptacle having a rarefied atmosphere consisting of neon, ofelectrodes mounted in said receptacle near one wall thereof and adjacenteach other,

.and'a barrier between said electrodes and extending away from them intothe body of the receptacle to compel the dischargeto pass from oneelectrode through the neon and around said barrier to the otherelectrode. I

2. In a gaseous conduction lamp, the combination of a bulb containingrarefied neon, electrodes located at or near the neck of said bulb, anda tubular barrier mountedin said bulb to separate said electrodes andjoined to the bulb near the neck thereof, said barrier extending to apoint adjacent the tip of the bulb.

3. In a gaseous conduction device, the combination with a sealedinclosure containing rarefied neon, of an electrode comprising a body ofaluminum shaped to pro vide cavities exposed to the neon, and metallicsodium in said -cavities.

4:. In a gaseous conduction lamp, an electrode consisting of an openaluminum container and metallic sodium in said container.

5. The combination with a closed receptacle containing rarefied neon, ofa negative electrode having one 'or more discharge receiving cavities ofcontracted dimensions and surfaces which receive and are heated by theelectric discharge.

6. In a gaseous conduction lamp, the combination with a sealedreceptacle having thercin a rarefied atmosphere, electrodes mounted insaid receptacle, at least one of said electrodes being hollow, having acontracted opening therein and containing metallic sodium.

7. In a gaseous conduction lamp the combination Mum sealed receptaclehaving a rarefied atmosphere consisting of neon, of electrodes mountedin said receptacle near one wall thereof and adjacent each other and abarrier between said electrodes and extending away from them into thebody of the receptacle, said electrodes being composed in part at leastof metallic sodium.

8. In a gaseous conduction lamp the combination with a sealed receptaclehaving a rarefied atmosphere consisting of neon, of electrodes mountedin said receptacle near one wall thereof and adjacent each other and abarrier between said electrodes and extending away from them into thebody DANIEL MOFARLAN MOORE.

Witnesses S. N. WHITEI-IEAD, J. ELKINS.

